Germany warns against giving up on Ukraine truce

German Foreign Minister Frank-Walter Steinmeier, fresh from a tense mission to Ukraine and Russia, said Wednesday he had not given up on a tattered truce agreement between the sides.

Steinmeier warned after talks in Berlin with his Polish counterpart Grzegorz Schetyna against calling the two-month-old ceasefire agreed in Minsk "history".

The German minister said some of his European Union colleagues, whom he did not name, were beginning to doubt whether the agreement could survive due to continuing clashes in eastern Ukraine.

Steinmeier, who on the whirlwind tour Tuesday met with the presidents of both Ukraine and Russia, Petro Poroshenko and Vladimir Putin, admitted the conflict was "still far from a sustainable deescalation".

He said there was the danger that the "small momentum" generated by the Minsk ceasefire deal could now be lost.

Schetyna said all EU countries needed to see the resolution of the Ukraine conflict as their "shared concern", calling the crisis "a test for Europe's ability to take political action".

On his talks in Moscow, Steinmeier said it was clear there were "dramatically differing perceptions" of events in Ukraine, with Putin citing the February ouster of Ukraine's pro-Russian president Viktor Yanukovych as the root cause of the conflict.

Steinmeier called Moscow's subsequent annexation of the Crimean peninsula a "clear violation of international law".

"We must not accept borders being shifted 70 years after the war," he said.

Deadly fighting has rumbled on in Ukraine's east despite the ceasefire deal that has halted significant offensives but failed to stop shelling at strategic flashpoints along the frontline.

Over 4,000 people -- mostly civilians -- have been killed in the conflict since April, the United Nations said.